keymile: common: update to set_env_hex(), fix "pram" radix

keymile: common: update to set_env_hex(), fix "pram" radix

Replace instances of sprintf()/set_env() for setting hexadecimal
values with set_env_hex().

In set_km_env() the "pram" variable was set to an hexadecimal
value, while initr_mem() expects an unsigned decimal, so use
set_env_ulong() instead.

Signed-off-by: Niel Fourie <[email protected]>
Cc: Holger Brunck <[email protected]>
Cc: Heiko Schocher <[email protected]>
Reviewed-by: Stefan Roese <[email protected]>
[Rebased]
Signed-off-by: Priyanka Jain <[email protected]>